It is now commonplace for fuel dispensing systems to blend different octane grade fuels into an intermediate grade for consumption. Previously, a fuel dispenser was connected to as many underground tanks as grades of fuel offered from a given dispenser. That is, there was a one to one correspondence between the octanes offered and the number of underground tanks. Each nozzle simply drew from a tank of a particular octane rating. This required expensive installation and maintenance of several underground tanks.
Currently, however, gas stations can provide many grades of fuel from only two underground tanks, a high and a low octane tank, by blending the fuels of each into the desired intermediate grade. This proves much more economical and efficient due to the reduction in the number of underground tanks.
Fuel blending is a well-known concept as evidenced by the representative prior art patent references cited below. The techniques and mechanisms used to achieve fuel blending, however, are quite variable.
U.S. Pat. No. 4,404,984 issued to Jones entitled "Gas-Liquid Mixing Metering System" describes a blender which differentially senses liquid pressure and gas pressure and provides adjustment means for a valve in order to increase or decrease pressure based on current requirements.
U.S. Pat. No. 5,139,045 issued to Ensign entitled "System for Dispensing a Fuel Mixture" describes a system for blending two different fuel grades to produce a third intermediate fuel grade.
U.S. Pat. No. 5,125,533 issued to Gayer et al. entitled "Variable Blending Dispenser" describes a variable valve system using flow-meters to calibrate and correct errors in a fuel blending system.
U.S. Pat. No. 3,999,959 issued to Bajek entitled "Motor fuel Blending Control System" describes a system for mixing two gasoline streams having dissimilar octane ratings.
The present invention is advantageously distinguishable from each of the above references in the mechanisms and methods it uses to achieve fuel blending.